Filamentary material



United States Patent "ce This invention relates to the production of filamentary material having improved properties.

There exists a wide variety of polymers possessing certain desirable properties which make them useful when formed into filamentary material but which are relatively difficult to dye. For example, it is diificult to dye filamentary material of these polymers by means of the standard dyeing procedures applied to more easily dyed materials such as wool, cotton and cellulose secondary acetate. This is especially true when the so-called disperse dyes which are ordinarily applied to cellulose secondary acetate are being used.

It is an object of this invention to provide improved filamentary material of ordinarily difiicultly dyeable polymers. It is a further object of this invention to provide filamentary materials of ordinarily difiicuitly dyeable polymers which are more easily dyed with disperse dyes. Other objects will become apparent from the following detailed description and claims.

In accordance with one aspect of the invention, a difficultly dyeable polymer is formed into filamentary material, the individual filaments of which have a denier no greater than 25, preferably no greater than 6, in the presence of a compound of a particular class termed herein as an additive, which has the effect of improving the dyeability of the polymer. If the polymer is being formed into filaments by means of dry spinning techniques the additive may be incorporated into the spinning solution. An alternative procedure in the case of wet spinning is to incorporate the additive in the coagulating or spin bath. When it is desired to melt spin the polymer the additive may be mixed with the melt prior to spinning. When the filimentary material is prepared using any of these techniques the additive is present throughout the cross-sections of the individual filament, distributed in such cross-sections in a substantially uniform manner.

In general filamentary material of an ordinarily dlr cultly dyeable polymer containing an additive of this invention has substantially improved dyeability with disperse dyes as indicated by an increased dyeing rate and a higher rate of practical dye exhaustion. For example, as expressed quantitatively, the additive-containing filamentary material of this invention will take up at least preferably to 1000% more dye based on the Weight of the filamentary material when dyed for at least A hour, preferably /2 to 8 hours in a standard aqueous dye bath than a substantially identically prepared and treated material but containing no additive which is dyed with the same dyebath in substantially the same manner.

The test dyebath may contain, for example, /2 to 8% of a disperse dye of the class Well-known in the art to be suitable for the dyeing of cellulose secondary acetate,

3,l72,723 Patented Mar. 9, 1965 such as Interchernical Blue GSF (Anthraquinone Color Index No. Disperse Blue 27) and Eastone Red NGLF (CI. Disperse Red 35).

The liquor to filamentary material in the test dye-bath may vary, for example, from 20:1 to infinity, preferably from :1 to 100:1, and the dyeing temperature from to C.

In addition to the above improvement in dyeability, the additive containing filamentary material, preferably after being changed to an annealed or crystallized state, e.g., by a heat treatment, has a safe-ironing temperature no lower than 20 C. less than that of substantially identically prepared and treated material containing no additive, and is preferably equal to that of the non-additive containing material. Expressed in absolute terms the safe-ironing temperature is preferably not less than 210 C.

It is preferable that the additive-containing filamentary material also have the following properties:

The discoloration after a standard heat treatment, e.g., 15 minutes to 10 seconds at 180 to 300 C. as determined by International Grey Scale rating of Color Change is no more than 1.5 NBS (National Bureau of Standards) units less than that obtained for substantially identically prepared and treated non-additive containing material. The relationship between International Grey Scale of Color Change and color difference expressed absolute color rating in NBS units is shown in the 1959 edition of Textile Manual and Yearbook of the American As sociation of Textile Chemists and Colorists, page 88.

The tenacity expressed as grams per denier of the dry, additive-containing filamentary under ordinary conditions, e.g., 23 C. and 65% relative humidity, is no less than 80% of that of a substantially identically prepared and treated material containing no additive and is preferably at least equal to the tenacity of the nonadditive containing material.

In addition to the above, it is preferable that the additive-containing filamentary material also meets the following tests.

The washfastness expressed as change in shade of the additive containing filamentary material dyed to 0.4 to 6% of dye takeup based on the Weight of the filamentary material using a dyebath and dyeing conditions Within the ranges set out above in the discussion of dyeability, when determined using a standard washfastness test, after the removal of surface dye, is not more than 2.0 NBS units less that that of a substantially identically prepared and treated filamentary material containing no additive which is dyed in the same manner as determined by International Grey Scale rating of Color Change. In many cases, the washfastness of the additive containing material is at least equal to that of the non-additive containing material, the change in shade in no case being more than 1.5 NBS units. A standard washfastness test which may be used is, for example, the standard A.A.T.C.C. Test #3 C.) for manufactured organic fibers, described in the 1950 edition of the Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, page 87.

The lightfastness of additive containing material dyed to 0.2 to 1% of dye takeup using a dyeba-th and dyeing conditions within the ranges set out above in the discussion of dyeability is not more than 2 NBS units less than that of a substantially identically prepared, treated, and dyed non-additive containing material as determined by International Grey Scale of Color Change, when subjected to a standard lightfastness test for 20-40 hours. Preferably, the lightfastness is equal to that of the nonadditive containing material. A standard lightfastness test which may be used is 20 to 40 hours of fadeometer exposure using the standard A.A.T.C.C. Atlas fadeometer procedure as described for example in the 1958 edition of the Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, pages 99,

100 and 102.

A particularly important group of compounds which may be used as additives under this invention are the aryl phosphates, e.g., the tri-aryl phosphates such as triphenyl phosphate, tricresyl phosphate, o-phenylphenyl bis(phenyl) phosphate, tris(o-phenylphenyl) phosphate, tr-i(2,5-dimethylphenyl) phosphate, tri(2,6-dimethylphenyl) phosphate, tri(3,5-dimethylphenyl) phosphate, tri- (2,3,5-trimethylphenyl) phosphate, tri(beta-naphthyl) phosphate, the dialkyl monoaryl phosphates such as dinethyl monophenyl phosphate and diethyl monophenyl phosphate, the (ii-aryl monoalkyl phosphates such as diphenyl monomethyl phosphate and dicresyl monomethyl phosphate, and the his phosphate of alkylene glycols and dialkylene rglycols such as his (dicresyl phosphate) of diethylene glycol.

Another group of compounds which may be used as additives under this invention are the his aryl urethanes having the following formula:

0 ArNHii'-OR 'RO-iNH-Ar Where Ar is an aryl group eg phenyl, naphthyl, and phenylphenyl and the latter radicals substituted with various radicals, e.g., lower alkyl such as methyl ethyl and propyl; R is an alkylene group containing up to 6 carbon atoms, e.g., ethylene and methylene and Y is oxygen or sulfur. The Ar and R groups may be the same or different. A particularly valuable compound within this formula is diethylene glycol bis(phenyl urethane) wherein the Ar groups are phenyl, the R groups are ethylene, and Y is oxygen. Another specific compound within this formula is the bis(phenyl urethane) of di(beta-hydro-xyethyl) sulfide wherein the Ar groups are phenyl, the R groups are ethylene and Y is sulfur.

Another group of compounds useful as additives are diesters having the following formula:

where the Ar, R and Y groups have the same definitions as set out above in connection with the bis-urethanes. Included within this formula are diethylene glycol bis(benzoate) and the his (benzoic acid) ester of diQbeta-hydroxyethyl) sulfide.

An additive of this invention may, in general, be a monomeric compound having molecular Weight of below 700, e.g., 250 to 600. It may be an ester, e.g., of a phosphoric or carboxylic acid.

The additive is used in an amount such that a minor portion remains dispersed throughout the cross-section of the individual filaments in a substantially uniform manner. In many cases the amount of additive in the filamentary material will be in the range of 3 to preferably 5 to 12% by Weight.

The nature of the additive used will depend to some extent on the nature of the polymer and the method used in the manufacture of the filamentary material. Thus the additive must be compatible with the polymer under ordinary conditions. It must also be compatible with the spinning solution in the case of dry spinning, with the spin bath in the case of wet spinning, and with the melt in the case of melt spinning, in view of the method of incorporation used for each of the different spinning A techniques. Moreover in the case of melt spinning the additve is preferably stable at the temperature of the melt.

The invention may be applied to a wide variety of difficultly dyeable filamentary material, e.g., material which cannot be easily dyed with the so-called disperse dyes. In general these materials are considerably more difiicult to dye with disperse dyes than conventional cellulose secondary acetate. As an indication of the contemplated material, a sample of filamentary material prepared from a polymer containing no additive may be dyed using a standard dyebath and dyeing conditions within the ranges set out above in the discussion of dycability. The dyebath and dyeing conditions shown in Example I below, may, for example be used as the standard in testing the dyeability of a filamentary material. If the dye takeup after 90 minutes of dyeing is less than 1.4% of dye powder based on the weight of the filamentary material, the polymer may be considered to be an ordinarily difiicultly dyeable material.

A significant group of materials falling within the above category are cellulose triesters of fatty acids such as acetic, formic, propionic, butyric and the like which contain fewer than about 0.29, and preferably fewer than about 0.12 free hydroxyl groups per anhydro glucose units in the cellulose molecule. A particularly important material within this group is cellulose triacetate containing more than 59% and preferably more than 61% of acetyl groups calculated as combined acetic acid.

Another very important group of difficultly dyeable materials are the fiber-forming linear polyesters of polyhydr-ic alcohols, e.g., glycols such as ethylene glycol, diethylene glycol, dimethylol cyclohexane and the like or mixtures thereof with polycarboxylic acids, e.g., dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, S-sulfoisophthalic acid, adipic acid and the like and mixtures thereof, as well as fiber-forming linear polyesters of hydroxyca r-boxylic acid, e.g., polyglycolic acid. A particularly important material Within this group is polyethylene terephthalate.

Gt her difficulty dye-able materials contemplated are fiber forming polyamides such as poly(polymethy-lene) terephthalamides adipamides and sebacamides in which the polymethylene groups contain 2 to 8 carbon atoms, e.g., polyheXamethy-lene terephthalamide and polyhexamethylene adipamide, polyaminoalkanoic acid, e.g., polyaminocaproic acid, fiber-forming polyurethanes such as the polyurethane formed from the bis (chloroformate) of butanediol and tetra-methylene diamine, fiber-forming polymers and copolymers of acrylonitri lc, e.g., containing more than 40 percent and preferably more than percent of lac-rylonitnile residues in the polymer chain, e.g., polyaorylonitrile and copolymers of acrylonitrile and various comonomers, e.g., vinyl esters such as vinyl acetate, vinyl amines, vinyl pyridine, methyl vinyl pyridine, chloroethyl vinyl ethers, etc., fiber-forming polymers of vinylidene cyanide such as those containing at least 50% of vinylidene cyanide in the polymer chain, e.=g., a copolymer of 50% vinylidene cyanide and 50% of vinyl acetate and fiber-forming polyolefins such as polypropylene.

The aryl phosphates, especially the triaryl phosphates, are particularly advantageous in improving the dyeability of filamentary material while preserving its other properties. In the 'case of cellulose triesters, e.g., cellulose trincetate containing at least 59% and preferably at least 61% of acetyl groups calculated as combined acetic acid and aromatic polyesters, e.g., polyethylene terephthalate, the preferred aryl phosphates are triaryl phosphates in which at least one of the aryl groups contains 2 benzene rings, e.g., a phenylphenyl group. A particularly preferred compound with cellulose tria'cetate is o-phenylphenyl bis (phenyl) phosphate while a particularly preferred additive with polyethylene terephthala-te is tris (o-phenylphenyl) phosphate.

The disperse dyes which are more easily applied to filamentary material as a result of this invention are generally those which are applied in the form of a dispersion in an aqueous bath. These dyes have long been applied to secondary cellulose acetate and include azo dyes, anthraquinone dyes and aryl amine dyes. Specific examples of these dyes are 2-nitro-4-sulfonanilido diphenylamine; 4-ethoxy-2-ni-trodiphenylanrine-[i-hydroxypropylamide; 4-nitro-2-methoxyphenyl azo 4'-bis (betahydroxye-thyl) amino-2-acetylaminobenzene; 4-nitro-2-methylsulfonephenyl azo 4'-(N-beta-hydroxyethyl-N-difiuoroethyl) aminobenzene; 4-nitro-2-chlorophenyl azo 4'-bis(beta-hydroxyethyl) amino-2-methylbenzene; 1-hydroxyethyl-amino-4-hydroxyethylamino-5- 8-hydroxy anthraquinone; 4'-nitrophenyl azo 4-di-fi-hydroxyethylamino2-acetaminobenzene;

a mixture of 1.4-di(hydroxy-ethylamino)-5,8-dihydroxy anthraquinone and 1-amino-4-anilido anthraquinone; 1,5 dihydroxy 8 nitro-4-(meta-alpha-hydroxyethyl) anilido anthraquinone; 1,8-dihydroxy-4-(para-beta-hydroxyethyl) anilido-S-nitro anthraquinone; 1-amino-4- anilido anthraquinone; and 2,4-dinitro-6-chlorophenyl azo 4'-bis (hydroxyethyl) amino-2-acetylamino-5-methoxy benzene. These dyestufis, as sold, are in the form of mixtures of a dispersing agent, such as sodium lignosulfonate or the sodium salt of formaldehyde-naphthalene sulfonic acid condensation product, with the actual dye material, and usually contain about 30 to 45% of the actual dye material.

In many cases, the additives of this invention have surprisingly little effect on the tenacity of the fibers considering that the additives have low molecular weights when compared with the fiber-forming polymer. For example, in the case of cellulose triacetate, tenacities are obtained with an additive-containing material well in excess of 90% of, and often equal to, that of an otherwise identical fiber without additive. Similarly, in the case of polyethylene .terephthalate, tenacities are obtained with an additive-containing material in excess of 90% of an otherwise identical material without additive.

An additional advantage obtained with cellulose triacetate containing many of the additives of this invention is an improved resistance to fading of the dyed material as a result of the action of ozone (O-fading resistance). Moreover, it has been found that cellulose triacetate containing an additive of this invention may be heat treated at a lower temperature, e.g., about 10 to 25 C. lower, than an otherwise identical material containing no additive to obtain an equivalent safe-ironing temperature. This lower heat treatment frequently results in a smaller loss of tenacity than occurs when the material is heat treated at a higher temperature.

It is surprising that despite the fact that the additives of this invention are generally of relatively low molecular weight as compared with cellulose triace-tate and have the eflfect of lowering the glass-rubber transition temperature, they do not appreciably effect the safe-ironing temperature of the triacetate. In contrast, polymeric materials whether or not they lower the glass-transition temperature of the triacetate, generally adversely affect its safe-ironing temperature.

The invention will now be further illustrated by the following examples in which all percentages are by weight unless otherwise indicated.

hydroxy- Example I In each of the examples the results obtained from various tests carried out on additive-containing yarn are compared with those obtained from the same tests carried out on a substantially identically prepared yarn of the same material which contains no additive.

Cellulose triacetate containing 61.7% of acetyl groups calculated as combined acetic acid and o-phenylphenyl bis (phenyl) phosphate as additive were dissolved in a solvent consisting of 91% methylene chloride and 9% of methanol to yield a clear spinning dope containing 21.5% of cellulose triacetate and 2.1% of o-phenylphenyl bis (phenyl) phosphate. The dope was dry spun in a conventional manner to yield a 40 filament yarn of denier with 0.1 turn of S-twist per inch and containing 10% of additive based on the weight of the cellulose triacetate. The individual filaments were thus 3.75 denier.

To test the dyeability of the yarn, a 5 gram sample in the form of a knit hoseleg was scoured at 70 C. for /2 hour in a scour bath containing 400 ml. of distilled water, 0.5 gram per liter of Igepon T77 surface active agent (C H CO.N(CH ).C H SO Na) and 0.5 gram per liter of Calgon fused sodium metaphosphate (Na P O The scoured sample was then rinsed in distilled water at 23 C. and air dried.

A standard aqueous dyebath was prepared containing 0.5 gram per liter of Igepon T-77 surface active agent, 0.5 gram per liter of Calgon and 0.5 gram per liter of a commercial dye powder of Interchemical Blue GSF, Anthraquinone Color Index No. Disperse Blue 27, and having the formula The scoured 5 gram sample was then agitated with 400 ml. of the above dyebath at 92 C. for 90 minutes in an Atlas Launderometer as described in the 1958 edition of the Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, pages 83 and 84. The dyebath thus contained 0.2 gram of dye powder or 4% based on the weight of the fiber, and the liquor to yarn ratio was 80:1.

After removing the sample from the dyebath, it was mildly washed for 4-5 minutes at 35 C. in a solution or" 0.5 gram per liter of Igepon T77" and 0.5 gram per liter of Calgon in distilled water. The dyed sample was rinsed three times in distilled water, excess water was squeezed out and the sample dried in air at room temperature.

The dye content as determined by conventional methods of colorimetry after dissolving the dyed sample in an appropriate solvent, was 2.04% of dye powder based on the weight of the yarn.

Other properties of the additive containing yarn of this example were as follows:

The safe-ironing temperature of hoseleg knitted from the additive-containing yarn which were heat treated at 215 C. for 60 seconds before testing was 240 C. and the same safe-ironing temperature could be obtained by similarly heat treating at 205 C.

The retention of whiteness of scoured hoseleg prepared from the additive containing yarn of this example after heat treatment at 215 C. for 60 seconds in terms of International Grey Scale Rating of Color Change (IGS) was 4 plus or 1 NBS unit of color change.

The tenacity of the dry yarn at 23 C. and 65% relative humidity was 1.12 grams per denier.

The washfastness expressed as shade change of hoselegs prepared from the additive containing yam of his example after being dyed as described above and exposed to the standard No. 3 A.A.T.C.C. wash test at F., was 4 plus (IGS) or 1 NBS unit of color change as compared with the unwashed material when the dyed yarn was heat treated at 210 C. for 1 minute, and was 4 (168) or 1.5 NBS units of change when the yarn was not heat treated.

The lightfastness of hoseleg knitted from the additive containing yarn of this example and dyed as described above, which yarn was in the fadeometer for 20 hours using the standard A.A.T.C.C. Atlas fadeometer procedure, was 45 (IGS) or less than 1 NBS unit of change from the unexposed material both when the dyed sample was heat treated at 210 C. for 1 minute and when it was not heat treated.

The properties of the control yarn, i.e., cellulose triacetate prepared and tested as described above but containing no additive were as follows:

Dye takeupl.10% or" dye powder based on the weight of the yarn.

Tenacity-4.04 to 1.19 grams per denier at 23 C. and 65% relative humidity.

Safe-ironing temperature of heat treated yarn240 C.

Washfastness (shade change)4 plus (IGS) or 1 NBS unit when the yed yarn was heat treated at 210 C. for 1 minute and 4 (IGS) or 1.5 NBS units when the yarn was not heat treated.

Lightfastness45 (IGS) or not more than 1 NBS unit both when the dyed yarn was heat treated at 210 C. for 1 minute and when the yarn was not heat treated.

Thus, the additive-containing yarn took up 85% more dye after 90 minutes of dyeing than the control yarn. Moreover, the safe-ironing temperature, tenacity, washfastness and lightfastness of the additive-containing yarn Were equivalent to that of the control yarn.

The safe ironing temperature, referred to above, is determined by the use of a standard hand iron having a weight and sole plate area such that the pressure is 0.24 pound per square inch. The test is conducted by heating the iron until a selected 2-inch-square area of the sole plate adjacent the tip of the iron has the desired temperature. A 1 /2 inch square of the fabric to be tested is placed on an ironing surface comprising a foam rubber pad covered with cotton flannel, and the iron is then placed on the fabric so that the aforesaid selected area of the sole plate covers the fabric. The placing of the iron is carried out by hand without any lateral motion of the iron on the fabric and without any application of hand pressure to the iron on the fabric. After the iron has rested on the fabric for exactly seconds, the iron is lifted straight up otf the fabric. The test is repeated with the iron heated in 10 C. increments for each test until there is evidence of damage to the fabric, e.g., until the fabric sticks to the iron, becomes boardy or changes in color. The maximum safe ironing temperature is that temperature which is 10 C. below the temperature at which the first sign of damage to the fabric occurs.

In addition to the advantages shown above in connection with the additive-containing yarn of Example I, this yarn also possesses the following advantages when compared with substantially identical material containing no additive:

Better O-fading resistance;

Less shade change on heat treatment;

Better balance of dye exhaustion;

Lower saponification rate on treatment with alkali; Improved abrasion resistance;

Dissipates static electricity more readily.

Example II The yarn preparation and testing procedures of Example I were repeated except that the additive was his (phenyl urethane) of diethylene glycol. The results obtained were as follows:

Dye takeup1.48% of dye powder based on the weight of the yarn after 90 minutes of dyeing time.

Safe-ironing temperature after heat treatment--240 C. This result could be obtained by heat treating at 205 C. for the same period.

Retention of whiteness on heat treatment-4 plus (IGS) or 1 NBS unit.

Tenacity-1.07 grams per denier.

Washfastness (shade change)4 plus (IGS) or 1 NBS unit when the yarn was heat treated at 210 C. for 1 minute and 4 (IGS) or 1.5 NBS units when the yarn was not heat treated.

Lightfastness45 (IGS) or not more than 1 NBS unit both when the yarn was heat treated at 210 C. for 1 minute and when the yarn was not heat treated.

In this example, the additive-containing yarn took 35% more dye than the control yarn after minutes of dyeing with no sacrifice in other properties.

Example Ill 10 parts of triphenyl phosphate was stirred into 90 parts of previously dried molten polyethylene terephthalate at 282 C. under nitrogen and mixing was continued for 1 hour. The mass was then melt spun and drawn in a conventional manner to yield a denier yarn of 40 filaments each individual filament being 3.75 denier.

As a control a sample of the same polyethylene terephthalate containing no additive was melt spun and drawn in substantially the same denier. The two samples were then knitted into 5 gram samples of hoseleg and dyed and tested as described in Example I. The results are as follows:

Dye takeup of additive-containing yarn was 2.08% and of non-additive yarn was 0.53% of dye powder based on the weight of the yarn.

Safe ironing temperature of both additive-containing yarn and non-additive yarn Was 220 C.

Tenacity of additive-containing yarn was 4.2 grams per denier and of non-additive yarn was 4.6 grams per denier.

Washfastness (shade change) of additive-containing yarn was 4 (IGS) or 1.5 NBS units and of non-additive yarn was 3-4 (IGS) or about 2.5 NBS units.

Lightfastness of additive-containing yarn and nonadditive yarn was 4 (IGS) or 1.5 NBS units.

The inherent viscosity of the polymer determined at 25 C. in 0.1% solutions of 10 parts of phenol and 7 parts of symmetrical trichlorophenol was 0.64 for the addi five-containing blend corrected for the presence of additive and 0.58 for the non-additive control before spinning. The inherent viscosities after spinning were 0.67 for the additive-containing material corrected for the presence of additive and 0.55 for the non-additive control.

Thus, the additive-containing yarn of this example took up 290% more dye after 90 minutes of dyeing than the non-additive yarn with no sacrifice in the other properties.

The fact that the incorporation of additive does not promote degradation in the melt is indicated by the slightly higher inherent viscosity of the additive-containing melt than that of the non-additive containing melt. Furthermore the extrusion rate at spinning temperature indicated that the additive had no effect on melt viscosity. Moreover the tenacities obtained with the additive-containing and non-additive containing yarn are surprisingly similar since it might be expected that the incorporation of a low molecular weight compound in the polymer melt would lower the tenacity of the resulting yarn considcrably.

Example IV The procedure of Example III was followed except that the additive-containing blend contained 5% of tris (ophenylphenyl) phosphate as additive instead of the triphenyl phosphate and the blend was mixed for 30 minutes rather than one hour. After mixing the inherent viscosity of the additive-containing blend was 0.55 and that of the non-additive control was 0.54.

The additive-containing blend and the non-additive control were melt spun in a conventional manner and drawn to yield oriented crystallized filaments of about 7 denier which were of substantially the same white color. The

additive-containing filaments could take up substantially more dye than the non-additive control filaments with little significant sacrifice of other properties.

It can be seen form the above examples that the additives of the invention improve the dyeability of difiiculty dyeable, fiber-forming materials without substantial sacrifice of various other properties. Thus, the conventional methods of obtaining desired shades of these materials, e.g., the use of dye carriers and accelerants and/ or long dyeing times, which are often difiicult and expensive to carry out, may be avoided or minimized by means of the process of this invention. Furthermore, these advantages are achieved at the time of manufacture of the filamentary material. This avoids the necessity for specific treatment modifications at the dyehouse which may not be equipped to readily effect such modifications; moreover, the loss of control in dyeing which may result from the use of modifications at the different dyehouses is also avoided by the process of this invention.

In addition to the product advantages resulting from applicants invention there are also process advantages. For example, in the case of dry spinning there is a decrease in the amount of solvent which must be recovered per pound of yarn produced since when the additive is incorporated in the spinning solution along with the polymer the total permissible concentration of additive plus polymer is greater than when the polymer is spun alone.

It is to be understood that the foregoing detailed description is merely given by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to se cure by Letters Patent is:

1. A filamentary material of a difiicultly dyeable polymer selected from the group consisting of cellulose triesters of fatty acids containing fewer than about 0.29 free hydroxyl group per anhydroglucose unit in the cellulose molecule, fiber-forming linear polyesters, fiber-forming polyamides, fiber-forming polyurethanes, fiber-forming polymers of acrylonitrile containing more than 40% of acrylonitrile residues in the polymer chain, fiber-forming polymers of vinylidene cyanide containing at least 50% of vinylidene cyanide residues in the polymer chain, and fiber-forming polyolefins, the individual filaments of which material are no greater than 25 denier and contain an adidtive throughout their cross sections such that (A) The dye takeup when the filamentary material containing said additive is dyed with a disperse dye is at least greater than that obtained when a substantially identically prepared and treated filamentary material of said polymer containing no additive is dyed with the same dye-bath under substantially the same conditions; and

(B) The safe-ironing temperature of the additive containing filamentary material is no lower than 20 C. less than that of identically prepared and treated filamentary material of said polymer containing no additive, said additive being selected from the group consisting of (I) aryl phosphates;

(II) compounds of the formula wherein Ar is aryl, R is an alkylene group containing up to 4 carbon atoms, and Y is a member of the group consisting of oxygen and sulfur; and

(III) compounds of the formula wherein Ar is aryl, R is an alkylene group containing up to 6 carbon atoms, and Y is a member of the group consisting of oxygen and sulfur.

2. The filamentary material of claim 1 having a retention of whiteness after being subjected to a temperature of 180 to 300 C. for 15 minutes to 10 seconds not more than 1.5 NBS units less than substantially identically prepared and treated filamentary material of said polymer containing no additive, as determined by International Grey Scale Rating of Color Change and the tenacity of said additive containing filamentary material is at least of identically prepared and treated filamentary material of said polymer containing no additive when measured under ordinary conditions.

3. The filamentary material of claim 2 having a washfastness expressed in shade change when dyed with a disperse dye no more than 2.0 NBS units less than that of substantially identically prepared, treated, and dyed filamentary material of said polymer containing no additive, as determined by International Grey Scale Rating of Color Change when each of said materials is subjected to the identical standard washfastness test, and the lightfastness of said additive containing material is not more than 2.0 NBS units less than that of substantially identically prepared, treated, and dyed filamentary material of said polymer, as determined by International Grey Scale Rating, when each of said materials is subjected to the identical standard lightfastness test.

4. The filamentary material of claim 1 wherein said additive is present in an amount of 3 to 15% by weight of said material.

5. The filamentary material of claim 1 wherein said additive is uniformly distributed throughout the crosssections of the individual filaments of said filamentary material.

6. The filamentary material of claim 1 wherein said additive is an aryl phosphate.

7. The filamentary material of claim 1 wherein said additive is a compound of the formula:

.wherein Ar is aryl, R is an alkylene group containing up to 4 carbon atoms, and Y is a member of the group consisting of oxygen and sulfur.

8. The filamentary material of claim 1 wherein said additive is a compound of the formula:

wherein Ar is aryl, R is an alkylene group consisting up to 6 carobn atoms, and Y is a member of the group consisting of oxygen and sulfur.

9. The filamentary material of claim 1 dyed with a disperse dye.

10. The filamentary material of claim 1 wherein said difficultly dyeable polymer is cellulose triacetate containing at least 59% of acetyl groups calculated as combined acetic acid.

11. The filamentary material of claim 1 wherein said diificultly dyeable polymer is polyethylene terephthalate.

12. Filamentary material of cellulose triacetate containing at least 59% of acetyl groups calculated as combined acetic acid containing an aryl phosphate throughout the cross-section of the individual filaments, said individual filaments each being no greater than 25 denier.

13. The filamentary material of claim 12 wherein said aryl phosphate is o-phenylphenyl bis (phenyl)phosphate.

14. The filamentary material of claim 12 dyed with a disperse dye.

l5. Filamentary material of polyethylene terephthalate containing an aryl phosphate dispersed throughout the cross-section of the individual filaments, said individual filaments each being no greater than 25 denier.

16. The filamentary material of claim 15 wherein said aryl phosphate is tris(o-phenylphenyl) phosphate.

17. The filamentary material of claim 15 dyed with a disperse dye. I

18. The product of claim 1 wherein said unmodified difilcultly dyeable material is such that it takes up less than 1.4% of dye based on the weight. of said material when a five gram sample of said material is agitated at 92 C. for 90 minutes with 400 milliliters of an aqueous dyebath containing 0.5 gram per liter of a surface-active agent having the formula C17H33CO.N(CH3) .C H SO Na, 0.5 gram per liter of fused sodium metaphosphate and 0.5 gram per liter of a dye having the formula 0 N02 ii OH washed for 4 to 5 minutes at 35 C. in an aqueous solution of 0.5 gram per liter of said surface-active agent and 0.5 gram per liter of fused sodium metaphosphate, rinsed three times in water, and dried in air at room temperature.

References Cited in the file of this patent UNITED STATES PATENTS Reid Nov. 10, Lilienfeld Feb. 20, Forse et a1. Sept. 18, Ellis June 26, Dreyfus Apr. 30, Clarke et a1. Nov. 26, Ellis Mar. 16, Strain Nov. 16, Nagel et al Apr. 1, Stern Apr. 28, Stern June 9, Lamborn Apr. 1, Ladisch Oct' 7, Marley Aug. 23, Gerbaux June 24, Reese Feb. 9, Blomberg Dec. 20, Salvin et al. May 2, Tanner Sept. 5, Tanner July 30,

OTHER REFERENCES Fortess: Amer. Dyestuff Reporter, August 1, 1955, pp. 

1. A FILAMENTARY MATERIAL OF A DIFFICULTLY DYEABLE POLYMER SELECTED FROM THE GROUP CONSISTING OF CELLULOSE TRIESTERS OF FATTY ACIDS CONTAINING FEWER THAN ABOUT 0.29 FREE HYDROXYL GROUP PER ANHYDROGLUCOSE UNIT IN THE CELLULOSE MOLECULE, FIBER-FORMING LINEAR POLYESTERS, FIBER-FORMING POLYAMIDES, FIBER-FORMING POLYURETHANES, FIBER-FORMING POLYERS OF ACRYLONITRILE CONTAINING MORE THAN 40% OF ACRYLONITRILE RESIDUES IN THE POLYMER CHAIN, FIBER-FORMING POLYMERS OF VINYLIDENE CYANIDE CONTAINING AT LEAST 50% OF VINYLIDENE CYANIDE RESIDUES IN THE POLYMER CHAIN, AND FIBER-FORMING POLYOLEFINS, THE INDIVIDUAL FILAMENTS OF WHICH MATERIAL ARE NO GREATER THAN 25 DENIER AND CONTAIN AN ADDITIVE THROUGHOUT THEIR CROSS SECTIONS SUCH THAT (A) THE DYE TAKEUP WHEN THE FILAMENTARY MATERIAL CONTAINING SAID ADDITIVE IS DYED WITH A DISPERSE DYE IN AT LEAST 10% GREATER THAN THAT OBTAINED WHEN A SUBSTANTIALLY IDENTICALLY PREPARED AND TREATED FILAMENTARY MATERIAL OF SAID POLYMER CONTAINING NO ADDITIVE IS DYED WITH THE SAME DYE-BATH UNDER SUBSTANTIALLY THE SAME CONDITIONS; AND (B) THE SAFE-IRONING TEMPERATURE OF THE ADDITIVE CONTAINING FILAMENTARY MATERIAL IS NO LOWER THAN 20* C. LESS THAN THAT OF IDENTICALLY PREPARED AND TREATED FILAMENTARY MATERIAL OF SAID POLYMER CONTAINING NO ADDITIVE, SAID ADDITIVE BEING SELECTED FROM THE GROUP CONSISTING OF (I) ARYL PHOSPHATES; (II) COMPOUNDS OF THE FORMULA 